I thought this issue was solved but I realised soon after posting that the system would crash under high CPU load. This would happen with/without SMP and the kernel would also crash when not using X at all. But I also have other problems which do seem to be specific to the nvidia driver.
So, in response to a suggestion in this thread I changed the PSU for a much more powerful one to no effect. I've also started over with a fresh Debian install onto a new external storage array, doing away with software RAID and reiser4 to simplify things.
I have been trying as many kernel versions as possible to see if there is one which works for me. For realtime audio I require my kernel to be patched with Ingo Molnar's 'realtime-preempt' patches, which limits my choice of kernels. Some of the patched kernels will not even compile (2.6.13-rt14).
I originally had the nvidia driver working under 2.6.17-rt8. The problem with this was the random crashes under high CPU load, and realtime preemption did not seem to be working properly (JACK daemon suffering from frequent xruns).
I have just tested 2.6.14-rt22 with an interesting result. Without X running I've not had any crashes yet. The open-source 'nv' driver is broken, as always. But if I start X with the 'nvidia' driver I suffer the exact same problem as I originally reported here (left display all white, right display all black, and complete lockup). However, the 'vesa' driver works fine, though without Twinview support.
To try and get the 'nvidia' driver working, I tried the same things as I did under 2.6.17:
- booting the kernel with 'noirqbalancer' option
- booting with 'noapic acpi=off' (2.6.14-rt22 crashes before init)
- recompiling Xorg with 'composite' disabled
- RenderAccel 0
- disabling TwinView
Annoyingly, Windows XP (32-bit) works perfectly, and has never crashed on me yet.
I am truly puzzled as to why this bug keeps coming back, in the meantime I can only think to try other kernels, maybe even going back to a realtime patched 2.6.12 and/or older 'nvidia' drivers.
I've attached a nvidia-bug-report.log with X running under the 'vesa' driver, since the 'nvidia' driver crashes the system. There are some kernel errors to note, perhaps a result of using the realtime patches.
Thanks for any help!